Numerous processes are in use and have been proposed for the conversion of organic compounds and feedstocks to more valuable organic compounds and more valuable feedstocks for use in the organic chemical and petrochemical industries, particularly organic compounds and feedstocks derived from petroleum sources.
One promising approach to such conversion has been the oxidative conversion of organic compounds to other organic compounds. However, in many cases, such oxidative conversion processes are not commercially viable, primarily because they are energy intensive, conversions of the feedstock are low, selectivity to the desired compounds is low and such processes cannot be utilized in a continuous manner. In most of such processes the feedstocks are contacted with a solid contact material. However, there is a difference of opinion among workers in the art concerning the nature of such processes, and, particularly, the function of the contact material and the manner in which such function is performed. For example, workers in the art have at one time or another suggested that the function of the contact material involves a purely physical phenomenon, an adsorption-desorption process, either of atomic or molecular oxygen, either on the surface or occluded within the solid material, oxidation-reduction, utilizing multivalent metals capable of oxidation-reduction, adsorption and desorption of the organic materials on the solid materials, a free radical mechanism, etc. Consequently, the solid materials utilized are referred to variously as "contact materials", "promoters", "activators" and "catalysts". Accordingly, in order to avoid functional categorization, the terms "solid contact material" or "solid contact materials" will be utilized in the present application.
Since many processes of the prior art are based on the theory that the contact materials function via adsorption-desorption of oxygen, oxidation-reduction, etc., such processes are operated in a cyclic manner by passing an oxidizing gas over the contact material, then contacting the feedstock with the oxygen-containing contact material, and, thereafter, reactivating or regenerating the contact material by again passing an oxidizing gas thereover. Such processes thus require undesirably high temperatures, are energy intensive, since the exothermic and endothermic reactions occur separately, equipment costs are high, because of the necessity for rapid cycling, and the contact material's useful life is comparatively short.
From the above, it is quite clear that the suitability of contact materials for the oxidative conversion of organic compounds is unpredictable. It is, therefore, highly desirable that new and improved contact materials for such use be developed, and that improved processes utilizing such contact materials be provided, particularly processes which lower the temperatures necessary, lower the energy requirements, are capable of being carried out in a continuous manner, extend the useful life of the contact material, improve the conversion of the feedstock and improve the selectivity to the desired products.
Of the various feedstocks for the organic chemical and petrochemical industries, olefins, such as ethylene and propylene are of particular interest and have become major feedstocks. Of these, ethylene is by far the more important chemical feedstock since the demand for ethylene feedstocks is about double that for propylene feedstocks. Consequently, there is a definite need for materials and processes for the conversion of relatively inexpensive feedstocks to ethylene. At the present time, ethylene is produced almost exclusively by the dehydrogenation or pyrolysis of ethane and propane, naptha and, in some instances, gas oils. About 75% of the ethylene is produced at the present time by steam cracking of ethane and propane derived from natural gas, since natural gas contains from about 5 volume percent to about 60 volume percent of hydrocarbons other than methane, with the majority being ethane. However, relatively severe conditions, particularly temperatures in excess of about 1000.degree. C., are required and, as indicated, such processes are highly energy intensive. In order to reduce the severity of the conditions, particularly temperature, numerous proposals to catalyze pyrolytic reactions have been made. While some of these processes do, in fact, reduce the severity of the conditions, the conversion of the feedstock and the selectivity to ethylene are still quite low. Of particular interest in this phase of the art, is the oxidative dehydrogenation of alkanes, particularly alkanes having from 2 to 7 carbon atoms, and, still more particularly, ethane. However, many of the processes for oxidative dehydrogenation, which have been proposed, are subject to some or all of the previously mentioned deficiencies.